Xerox WorkCentre 385 Service Manual page 168

Table 3: Hardware Interface Signal Descriptions
Signal PIN No. Type
RXAI 45 I
SEPCLK 85 O
ECLKIN1 25 I
RCVO 98 O
SWGAINO 99 O
TXATT[3:1] 38, 39, I
40
BYPASS 36 I
Circuit Description
Description
Receiver analog input
The input impedance of RXAI is greater than 1Mohm. An external ana-
log anti-aliasing filter with transfer function 21551.72/(S+11547.34) is
required between the line interface and the modem RAXI input. The
maximum input signal level into the anti-aliasing filter should not exceed
0 dBm.
Digital Loopback
Over-sampling Clock Output. 2.304MHz clock output. Normally tied
to ECLKIN1.
Over-sampling Clock Input. Input to the AFE's over-sampling clock
input pin. Normally connected to SEPCLK.
Disable Transmitter Output. "1" on this pin disables AFE's transmitter.
Normally connected to RCVI.
Externally connected to SWGAINI pin.
Auxiliary Signals
Analog Transmit Attenuation.
The host can cause the modem to attenuate the transmit analog output
in steps of 2dB from 0dB by using the three encoded TXATT[3:1] inputs
as follows:
TXATT3 TXATT2 TXATT1 Attenuation (dB)
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
The TXATT[3:1] lines may be connected directly to 0V or 5V, or to three
GPIO lines used as outputs to select the attenuation under the host pro-
gram control.
Receiver Highpass Filter Bypass Enable.
The state of this pin does not have any effect on the operation of the
modem, but it should tied to either +5V or ground.
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WorkCentre 385